Steam generator



June 1l, 1940. M. FRlscH STEAM GENERATOR FilAed Nov. 19, 19365Sheets-Sheet ATTORN EY June ll, 1940. M. FRlscH l 2,204,350

- y STEAM GENERATQR I v Filed Nov. 19, 1936 5 SheetsrSheet 3 June l1,1940. M. Freisml STEAM GENERATOR Filed Nov. 19, 193e 5 Sheets-*Sheet 4INVENTOR /V/l/r//v /fws ATTORNEY June l1, 1 940. M. FRlscH 2,204,350

` STEAM GENERATOR Fviled Nov. 19, 1936 5 Sheets-Sheet 5 INVENTORPatented June 11, 1940 UNITED PATENrroFFlCE I STEAM GENERAToR' MartinFrisch, Cranford, N. J., assigner to Foster l, Wheeler Corporation, NewYork,` N. Y., a corporation of N ew York Appiieation NovemberL 19, 1936,serialvNo.A 111,638

' 13 claims; (o1. 12a- 336iv This4 invention relates to steam generatorsandv more particularly pertains to steam generators of the verticalstraighttubeftype.

The general object of the invention is to pros vide a steam generator ofthe vertical straight tube type which incorporates the most desirablefeatures of modern practice with; the various component parts thereof sovarrangedthat the generator maybe readily adapted to meet lo very small,very large and all intermediate steam out any changein the width orlength, "andwith the arrangement such Aas to requireonly vvery low headroom for small unitsand less than the '.71 usual head room for largeunits than isA now required by units of conventional designand com,-l

parable capacity. v v i Further objects of the invention are To providea vertical, straight tube type gen- 3i erator which requires l'essheadroom, than confI ventional steam generators, and lessspace by reason ofthe eliminationv of vthe necessity for side aisles between generatorunits and thenecessity for tube Withdrawal .spaces aroundtheunit. fifiTo provide a steam generator ofthe type in, dicated Which-includes allessentials'necessary for high availability,reliability7 low maintenanceand high. efiiciency butI with the elimination, 'or the reduction to aminimum, of all costly ,details so' of design and construction such asoutside` water conventional designs. o

To provide a steam ygenerator of the type -indicated, having moreradiant heat absorbing sur- 45 face per cubic foot of furnacevolume thanin conventional units and in which maximum heat absorption in the boilerproper is obtained with a lower draft lossthanfis customary in conven-`tional types of generator units.

im To reduce the cost of field erectionof vertical straight tube steamgenerators.gbyly designing the unit so that a` larger proportionthereofm'ay be assembled inthe shop than is now customary. To simplifythe ysupportingframework kof a` indicated, in which superheat. controlmaybe the cost Wall connectionsvwhich are required by the usual.

steam generator of the type mentioned, so that a minimumamount Will berequired.y

To provide a steamgenerator of theftypefmen-v l o tioned, which will besuitable for outdoorlopera- `tion and such that no'building rorprotecting ).5

structure Will be required. o

To provide a steam generator of thev type designated, in Whichvit ispossible to increase the load range obtainable by arranging the furnace'volume with respect to the unit so that low 10 ratingA operation neednot result in excessive cooling .of the flame. v

yTo .provide a steam generator of the character readilyeffected. l

To provide a `verticalstraight tube steam generator in which theconvection superheater is so arranged with respect to therother xheating surface thatthere will bano directame impingementv on thesuperheater and the gases,

' particularly where the unit is fired with pulverizedcoal, Will make anabrupt change kin direction of flow before entering' the superheater sothat alargev proportion of the ashcarried thereby will be thrown outinto the furnace before the gases enter the superheater..A

To provide a steam generator of the character indicated having Aafurnace so arranged with respect tothe boiler'that every part ofthelfurnaceV Volume is effective, thus permitting when neces- .30

sary, higher rates of heat yliberation than is now customary inpractice.r`

To provide `a verticalstraight tube steam generator which may beconstructed Without any f' brick Work, if necessary, or if brick work is-de- 3,5

sirable, to havetheamount thereof a minimum andof very simple design. vY

y To provide a steam generator of the character A mentioned, the overallcost of which isless than of conventional unitsvof .equal surface 4,0`

and reliability. f In l,the preferred embodiment of thevinventionKherein disclosed, vthese and .other objects are attain'ed'gby providinga steam generator having' a vertical, straight tube boiler throughwhichthe 45 gas-flow is substantially parallel to `the drums,

'disposed between and flanked `by two Watercooled furnaces of standardbut minimum Width required for the best performance with pulveri'zed,liquid lor gaseous fuel, f thereby providing the boiler with ,atleasttwoexposures to radiant heat.

o In the other formrof .the invention herein disclosed, Vthe verticalstraight` .tube boiler"is.,pro vided with a single laterallydisposedjfurnace.

l The furnaces 1n schijfrems are `ventirely .water-1 si;

cooled or may be water-cooled except for the ring end and the oppositeend, if desired. The furnaces are red from the front of the boiler byburners disposed adjacent the top or bottom or both top and bottom ofthe front walls and thegases flow tothe rear of each of the furnaceswhere they turn vertically through the separate upper and lower streamscombine, mix and return to the front ends of the furnaces where theymake a change in their horizontal direction of `iow of 180 to enter theboiler tube bank. These tur'ns separate from the gas a substantialproportion of fly ash and cause it to deposit in the furnaces. Asuperheater is disposed at the inlet end of the boiler and by virtue ofthis location, possesses the characteristics of Aboth a radiant and aconvection superheater. After passing through the superheater, the gasesflow through the boiler in a direction parallel to the boiler drum andacross all of the boiler tubes, which are arranged in staggered rowsfrom front to rear, with the result that maximum heat absorption in theboiler proper is obtained with a lower draft loss than in conventionalunits. The gases leave the boiler at the central portion of the rear ofthe boiler and flow to additional heat recovery apparatus such as aneconoinizer and/or an air heater and thence into an induced draft fan.The boiler tubes are staggered but are readily removable into thefurnaces and the water wall and superheater tubes are also readilyremovable into the furnaces.

The nature, objects and advantages of the invention will be understoodfrom the following description considered in connection with theaccompanying drawings forming a part thereof and in which:

Fig. 1-is a transverse vertical sectional view of steam generatingapparatus embodying the invention, taken substantially on line I-I ofFig. 3;

Fig. 2 is a horizontal sectional view taken on line 2-2 of Fig. 1;

Fig. 3 is a longitudinal vertical sectional View, taken on line 3-3 ofFig. 1;

Fig. 4 is a side elevational View with parts in section;

Fig. 5 is a horizontal, partial sectional View, on an enlarged scale, ofthe area designated A in Fig. 2;

Fig. 6 is a partial vertical sectional view, on an enlarged scale, ofthe boiler header arrangement;

Fig. '7 is a transverse vertical sectional view of another `form ofboiler embodying the invention; and

Fig. 8 is a horizontal sectional view, taken on line 8-8 of Fig. 'l'.

Like characters of reference indicate the` same or similar parts in theseveral views.

Referring to Figs. 1 to 6 inclusive of the drawings, the steam generatorillustrated has a rectangular casing or setting including a front wallI0, a rear wall II and side walls l2 and I3. The generator is providedwith two spaced parallel furnaces I4 and I5 which are disposed adjacentthe side walls I2 and I3 respectively of the setting. The generator isalso provided with a steam generating section or boiler I6, which isdisposed intermediate the spaced furnaces but is somewhat shorter inlength. The furnaces and boiler are of rectangular configuration and aredisposed in parallel relationship, as shown.

The boiler consists of straight vertically disposed tubes I1 arranged inrows extending transversely to the axis of the boiler with the tube rowsarranged in spaced pairs or groups of two rows each, with the tubes inthe rows of each group arranged in staggered relationship, as clearly indicated in the drawings, particularly in Fig. 5. The lower ends of thesetubes are rolled into a plurality of square headers I8 which are spacedsomewhat from each other so that ash which separates from the combustiongases in the boiler may drop lfreely into the soot hopper i9 below. Theupper ends of the boiler tubes I1 are rolled into square headers 20which are arranged in two spaced rows extending longitudinally of theboiler. The headers I8 and 20 are arranged in staggered relationship, asshown more clearly in Fig. 6, that is to say, alternate headers aredisposed at higher elevations than the other headers. Downcomers 2|connect the lower end oi the boiler drum '22 with the central portionsof the lower square headers I8. These downcomers extend through thecentral part of the boiler but are segregated from' the boiler tubes andare protected from contact with the combustion gases by suitablerefractory or other material 23. If desired, a passage between thedowncomers may be provided for access. Headers 20 are connected toheaders 24 through upcomers 25 and headers 24 are connected to the upperportion of drum 22 through a plurality of risers 26. The boiler tubebank also includes a plurality of rows, ve rows in the form shown, ofboiler tubes 21 which are larger than the tubes I1. Tubes 21 mayconveniently be 3%, inches O. D., whereas tubes I1 may be 2 inches O. D.A superheater 28 consisting of a plurality of rows of 2 inch O. D. looptubes as shown, is disposed at the inlet end of the boiler I6 ahead ofthe boiler tubes 21 with respect to the path of flow of the gasesthrough the boiler. 'The side walls 29 and 30 of the boiler have a rowof 31/4 inch boiler tubes 3| disposed along the boiler side of thesewalls for their entire lengths. These tubes 3I are connected into theheaders I8 and 20. A plurality of rows of 31A inch O. D. tubes 32 and 33are disposed between the front ends of the side walls 29 and 30 of theboiler and the front wall I0 of the boiler setting to provide slagscreens for the gases entering the boiler trom the furnaces I4 and I5.These tubes 32 and 33 may be disposed, as indicated in Fig. 2, or one ormore rows of these tubes may be disposed in front of the superheater 28,if desired.

The boiler drum 22 is provided with a steam washer and drier 35 which ismore fully disclosed and claimed in the copending application of MartinFrisch and Walter F. Keenan, Jr., Serial No. 110,310, led November l1,1936.

A plurality of steam risers 3B connect the upper end of boiler drum' 22with a steam drum 31 disposed above drum 22 and transversely withrespect thereto. A steam line 38 connects steam drum 31 with the inletheader of superheater 28.

In the form of invention disclosed in Figs. 1 to 6 inclusive, the steamgenerating section or boiler I6 is suspended from supporting framework.This framework includes vertically disposed columns 39, one of which isplaced at each corner of the boiler section I6, spaced longitudinallydisposed girders 40 and 4I which are secured to the upper ends of thecolumns 39 and transverse girders 42 which extend between and aresecured to the girders 40 and 4I. The boiler drum is suspended by spacedcradles 43 which are supported by the spaced girders 42. The boilercirculating tubes and headers to which they are connected are suspendedby a plurality of hanger rods 44 which are secured at their upper 'endsto the girders 40 and 4I. The steam drum 31 issupported in cradles 45which rest upon the upper surface of girders 40 and 4I. With thisarrangement it will be seen that the steam gener ating or boiler sectionin its entirety,excepting the `steam drum 31, is supported by beingsuspended from `points or supporting members above the boiler section.

The furnaces cooled. However, for low capacity installations the firingwall and the rear wall may be installed Without water cooling. Thewaterwall tubes for each furnace are designated 46 and these tubes' a'resuitably connected by headers which are connected into the circulatingsystem. The furnaces are supported by columns 41, auxiliary columns 48vwhich aredisposed at the outerside walls of the furnace, main girders49vwhich are supported by the columns 41 and 39 and by a plurality ofauxiliary girders or beams 50 which extend between the columns 48. Asmaybe seen in Fig. 1, a plurality of hanger rods 5I whichvare connectedat their upper ends to the girders 40 and 4l aid in supporting portionsof the furnaces and the water walls thereof.

rods 52 from a beam 53 extending between the main girders 40 and 4|. o'

Each of the furnaces I4 and I5 isired byv a plurality of spaced fuelburners disposed in .the front wall I IJ of veach furnace. The burners55 are located adjacent the upper ends of the front walls I0 of thefurnaces and, burners 56 are disl posed adjacent the lower ends of thefront walls or pulverizing mill.

I0 of the furnaces as clearly shown in Figs. l, 3 and 4 of the drawings.These burners are arranged to project streams ,of fuel and air throughthe spaces between the water wall tubes 46 and may be arranged similarly'to the burners disclosed in the copending application `of MartinvFrisch, Serial No. 444,906, filed April `1*'1, 1930. Fuel and primaryair are supplied tof the burners through conduits 51 to which the fuelis supplied from any suitable source such as a storagev bin Secondaryairv for the burners is supplied through an air yconduitl 58 whichconnects with an air casing E9 disposed outwardly of the front wall I 0of the boiler casing. Air

vfrom the casing 59 is supplied to air ducts 60 and 6I disposedrespectively above and below' the fuel Anozzles, of the burners 55and.56. With the .burner arrangement disclosed, th-e stream of products ofcombustion producedby each of the burners may be directed horizontallythroughout the lengths of the furnaces or may be directed verticallyupward or `vertically downward depending upon the quantity and velocityof the air streams supplied through the air ducts 6I) and 6I. 'I'he fuelburners 55 and 56 direct separate spaced `streams ofA products ofcombustionV to-` ward the rear walls II of thelfurnace, adjacent towhich the upper `stream turns downwardly and then forwardly through anangle of 180 and the lower stream turns upwardly and then forwardlythrough approximately thesame angle. The two streams impinge upon andmix with keach other at points near the rear walls II of the furnace andsubstantially midway between the top and bottom walls of the furnace,after whichV they flow toward the, front `of the furnace as indicated inFigs. 3 and 4. Upon reaching the front end of each of the furnaces, thereturning streams of products -of combustion' turn horizontally `throughanangle V,0 '18Q and pass over the slag screens 32'ahd 33 and flow I4and I5 are entirely water v The superheater tubes as* .may be seeninFig. 3, are suspendedk by hanger into the chamber 62 disposed betweenthe two furnaces and the front end of the boiler section rvI6 and'impinge upon and mix with each other. These streams then makeanotherhorizontal turn through an angle of 90 and flow over the superheaterltubes 28, boiler tubes 21 and there-v after flow over vall of the boilertubes I1 after which 'they enter a iiue 63 disposed at the rear end ofthe boiler section I6. `The gases flow downwardly in the ue 63v through.the return bend vsection 64 and upwardly through the verticallydisposed lsection 65 ywhich delivers the gases to an induced draft fan66l which lin turn delivers them to a stack 61. In the form shown inFigl, an air heater 68 is disposed inthe flue section 65 and air issupplied to this air heater by a forced draft fan 69. Ifdesired, aneconomizer may be disposed in the return bend section 64 preferably atits inlet portion 10. l'

rlhe firing arrangement disclosed and the method of firing carried outthereby accomplishes several desirable results. Among these lmay bementioned the fact that all o f the furnace volume of each furnace isfully utilized. This will beapparent fromr an inspection of Figs. 3 and4, particularly wherein the lines designating the flow of the stream-sof products of combustion indicate that the gases flow throughsubstantially all portions of each of the furnaces. At the points orvzones where the upper and lower streams of products of combustionimpinge Vupon each other, intensive mixing occurs which acceleratescombustion to a vmaximum and reduces stratification of the gases to aminimum. Inasmuch as the gases and burning fuel `are forced to makertwochanges in directionof approximately 180/1 each prior to their enteringthe superheater and boiler, a larger proportion of suspended ash will beprecipitated within the furnaces thanin conventional units.

, The method -of ring disclosed herein is dis-` closed and claimed in aappending application of Martin Frisch, Serial ber 19,1936-, l

' The boilerr maybe fitted with a plurality of No. 111,639,filedNQverwrt' suitable -soot4 blowers disposed so as to face thesuperheater andwith several soot blowers placed under the superheaterand with a plurality of stationary pipe dust blowers 1I which are dis-`posed so that their nozzles open up into the main bank of yboiler tubesin the clearances between the lower headers I8. Additional soot blowersmay be provided to serve the economizer vand lancing doors may beprovided for cleaning advantages over the usual method of removing tubesfrom straight tubey boilers. These advantages are first, complete`elimination "of any danger of scoring the tube holes when .attemptingto remove bagged or blist-ered boiler tubes andcse'cond, no tube removalspaces in the front or rear of `the/boiler need be provided which meansthat a straight tube steam generator may be installed in spaces wherethe installation of standard straight tube boilers would be entirely outof the question. Additionally with this arrangement, the boiler drum maybe thinner than is required for benttube types of boilers because of thehigher ligament efficiency. For this reason and because the cost of thesimple square headers used will be lessnthan the cost of a mud drum, thecost of this type of boiler will be less for high pressures than forconventional types.

It will be perceived that each steam generating tube will have the fullcirculating head acting upon it. In this respect the boiler arrangementdisclosed herein is superior to conventional straight tube boilers inwhich the circulating head progressively decreases from row to rowtoward the top of the boiler. As a result, circulation difiiculties withthe type of boiler herein disclosed should be non-existent.

In the forms of the invention shown, the gases from both furnaces flowover the superheater 28.. However, if desired, the superheater may be soarranged that the gases from one furnace may pass over the entiresuperheater and the gases from the other furnace may by-pass or passonly over a part of the superheater. This arrangement may be effectedwithout the necessity of employing dampers or of by-passing any of thesteam generating surface.

Figs. 7 and; 8 illustrate more or less diagrammatically the inventionembodied in a boiler having a single furnace disposed laterally of thesteam generating section. In its essentials, this form of the inventionis the same as the form shown in Figs. 1 to 6. The boiler sectionincludes a plurality of vertical straight tubes 80 connected to aplurality of square headers 8| arranged in the manner shown in Fig. 6,with a plurality of downcomers 82 disposed along side wall 83. A singledrum 84 is disposed longitudinally of the boiler section at its upperportion thereof. The furnace 85 is entirely water cooled as shown, andburners 86 and 81 are disposed in the front wall 88 of the furnaceadjacent the upper and. lower portions thereof as shown in Fig. 7. ',Ihestreams of products of combustion from these burners flow through thefurnace and the boiler section as described in connection with Figs. 1to 6. After the gases have mixed and have returned to the front end ofthe furnace B5, they turn through an angle of 90 and pass over slagscreen 89, after which they make another turn of 90 and ow over thesuperheater 90, thence over the group of larger steam generating tubes9|,` after which they flow over the smaller steam generating tubes 80.The gases pass out of the boiler at the rear end of the steam generatingsection through a flue 92.

, The downcomers 82 may be shielded from contact with the combustiongases. The boiler tubes 80 and 9i are grouped similarly to the tubearrangement shown in Figs. 1 to 6 and each of these tubes is readilywithdrawn through the furnace 85 in the same manner as described inconnection with the other form of invention herein disclosed.

With these arrangements of component parts of a steam generator, it willbe perceived that a change in the vertical dimension only of thegenerator and the several component parts thereof will result in aproportional increase in furnace volume and heating surface, inconsequence of which steam generating units may be provided for anysteam output requirements whether large or small, by merely varying theheight of the unit without changing either the width or length thereof.In consequence, the same design may be utilized for `all steam outputrequirements, thereby eliminating the necessity for separately designinggenerators for every new use. By the use of a plurality of Water cooledfurnaces, it is possible to maintain the desirable ratio of watercooledsurface to the furnace volume or to the rate of fuel firing, as the sizeof the generator is at an end of the row of units or at someintermediate point which will permit access to the rear of the row ofunits. However, such aisles as may be necessary to the rear may be muchnarrower than in conventional arrangements because no access to any partof the units through the sides thereof is necessary for any purpose.

The heat recovery devices, such as air heaters and economizers as wellas the fans, may be disposed below the boiler and furnaces if desired,and may be located either on the operating oor or on a basement floor.Such an arrangement entirely eliminates the necessity for overheadsupporting structures for these devices.

Any essential auxiliary equipment may be located at the front of theunits on the operating aisles and all parts of the boiler are accessiblefor repairs from within the furnace. For removing the ash whenpulverized coal firing is used, a simple and low cost ejector system maybe installed with several openings connecting to the furnaces and withValves which are readily controllable from the front of the boiler. Suchash as may stick to the ash receiving hoppers at the bottom of theboiler and which cannot be blown away by the soot blowers can besimilarly removed.

With the arrangement disclosed, it is apparent that the furnaces may bebuilt in sections by sectionalizing the headers and that they may beshop assembled and shipped as units complete with insulation and casing.

Steam generating units embodying the invention are suitable for outdooroperation without any housing means therefor since all of the componentparts are included within or below the casing of the unit.

Although the invention has been disclosed in connection with steamgenerating units having one and twofurnaces respectively, which aredisposed in parallel relationship with each other and with the boilersection, it will be understod that more than two furnaces may beutilized in a unit without transcending the principles of the invention.It will also be understood that various changes may be made in thelocation and arrangement of the several component parts of the steamgenerating units without departing from the invention. Accordingly, itwill be understood that no intention is entertained to limit theinvention except by the scope of the claims appended.

What is claimed is:

1. A steam generator comprising a setting, a steam generating section inthe setting, an undivided furnace in the setting laterally disposed Withrespect to the steam generating section and steam generating section in`the setting, anvundi-V separated'therefrom', a gas passage at one endof the furnace connecting .the furnaceand said secA tion, and meansatsaidone end l' of the furnace for producing astream of products ofcombustion which ows throughthe'ffurnace toward the other end thereofand then returns to said. one end and-thereafter flowsrthroughsaid gaspassage andv throughthe steamgenerating section.

2. A steam generator comprising a setting, a steam generatingsection inthe setting, an undivided furnace in the'setting laterally disposed withrespect tothe steam generating section and separated therefrom,.a gaspassage at one end of the furnace connecting the-furnace and said section, and means, at said one end of the furnace for producing apluralityl of spaced streams of products of combustionjwhich ow throughthe furnace toward the otherend thereof and then return to said one endand thereafter flow through said gas p-assagevand through the steamgenerating section. v

3. Asteam generator comprising a setting having enclosing Walls, a steamgenerating section in the setting, a furnace inthe setting laterallydisposed withrespect to the steam generating section and separatedtherefrom by wall means, a gas passage at one end of the furnaceconnecting the furnace and said section, and burners at the upper andlower portions of said one end of the through said gas passageand'through the steam generating section.k i

4. A steam generator comprising a setting," a

steam generating section in the setting, an lundivided furnace in thesetting'at each vside of the .steam generating section and separatedfrom the latter, a gas passage at one end of each furnace y throughwhich gases flow into the same end of the steam generatingv section, andmeans at said one end of each furnace for producing a stream of productsof combustion which flows through the furnace toward the other endthereof and then returnslto said oneend and thereafter flows i' throughthe gas passage and the steam generating section. f

5. A steam generator comprising a setting, a steam generating section inthe setting, an 11n-- divided furnace in the setting at each side of thesteam generating section and separated from ther latter, a gasv passageat one end of each furnace f tion in the setting, a furnace in thesetting atA l each side of the steam-generating section and separatedfrom' the latter by wall means, a gas 'gas passage and through the videdfurnace in' the settinglaterally disposed "with respect to the steamgenerating section and separated therefrom', a gas'pas'sage at oneend'of the furnace connecting the furnaceand said secltion,1asuperheater disposed inthepath of flow of the gases between saidngaspassage and the steam generating section, and means at said one end ofthe furnace for .producing a stream of .products of combustion whichrflows through the furnace toward :the other end thereof andthen returnsyto said one end and thereafter flows through said gaspassage andvthrough the steam generating section.

8.1A steam steam generating section in the setting, an undigeneratorcomprising a setting, a fvided furnace in thesetting at yeach side ofthe end thereof and thenreturns to said one end and thereafter flowsthrough the gasfpassage and the steam generating section. f i

9. A steam generator comprising a setting, a steam vgenerating sectionin the setting, an undivided furnace in the setting laterally disposedwith respect to the steam generating section and separated therefrom, agas passage at onev end of the furnace connecting the furnace and saidsec tion, a. plurality of tubes forming a slag screen in the path of thegasesl flowing from the furnace to said section, and means at said oneend of the furnace for producing a stream'of products of combustionwhich flows through the furnace to ward the other end thereof and thenreturns to said one end and vthereafter flows through said steamgenerating section. y y

10.7A steam generator comprising a. setting, a

`steam generating section in the zsetting, anundividedfurnace inthesetting at each side of the steamgenerating section and separated fromthe latter, a gas passage at one end of each furnace through which gasesflow `into the same end of the steam generating section, a plurality oftubes forming a slag screen in the path of the gases y flowing from eachfurnace to said section, and

` meansat saidone end of each furnace for producing a stream of productsof combustion which flows through the furnace toward the other endthereof and then.y returns to "said rone end and thereafter flowsthrough the gas passageand the steam generating section, y

' 11. A steam generator comprising a setting, a steam generating sectionin the setting including a bank of steam generating tubes having theirmajor portions at least extending substantially transversely of thelongitudinal axis of said sec tion, a furnace` in the setting separatedfrom said section and wherein gases are produced for flow through saidsection, the path of flowof the gases through said sectionbeingtransverse to the steam generating tubes therein, downcomers within saidban-k of steam generating tubes, and means for shielding the downcomersfromv contact with the gases, said downcomers and shielding means beingdisposed to divide the gases flowing through said section into aplurality of paths.

12. A steam generator comprisingavsettng, a

steam generating section in the setting including a bank of steamgenerating tubes having their major portions at least extendingsubstantially transversely of the longitudinal axis of said section, afurnace in the setting separated from and at substantially the sameelevation as said section and wherein gases are produced for flowthrough said section, the path of oW of the gases through said sectionbeing transverse to the steam generating tubes therein, dovvncomersdisposed intermediate the side Walls of the steam generating section,and means for shielding the downcorners from contact With the gasesflowing through said section.

13. A steam generator lcomprising a setting, a

steam generating section in the .setting including a. bank of steamgenerating tubes having their major portions at least extendingsubstantially transversely ofthe longitudinal axis of saidsection, afurnace in the setting separated from and at substantially the sameelevation as said section and wherein gases are produced for flowthrough said section, the path of flow of the gases through said sectionbeing transverse to the steam generating tubes therein, downcomersdisposed intermediate the side Walls of the steam generating section,and means for completely shielding the downcomers from contact withl thegases flowing through said section.

MARTIN FRISCH.

